Well reamer with extensible and retractable reamer elements

ABSTRACT

A reamer for use in a drilling string for enlarging, scraping or smoothing a well bore, and having extensible and retractable cutting members operable by the pressure of the drilling fluid circulated through the string during the drilling operation. The cutting members may include a plurality of telescopingly arranged elements movably positioned on the body of the tool for radial movement inwardly and outwardly thereof relative to window openings in the body and having seal forming means positioned to prevent leakage through the openings. The cutting members and body are formed with inwardly and downwardly sloping end faces positioned for coaction to allow the cutting members to move inwardly toward their retracted position, aided by gravity, when the internal pressure in the string is shut off, and the members are also formed with beveled external, upper end faces, positioned for engagement with irregularities in the well bore to move the members toward their retracted positions upon upward movement of the string during the removal of the same from the bore.

United States Patent [72] Inventors Lafayette E. Gilreath;

Charles H. Pollard, P.O. Box 26171,

Houston, Tex. 77032 [21] App1.No. 765,157 [22] Filed Oct. 4, 1968 [45] Patented Jan. 19,1971

[54] WELL REAMER WITH EXTENSIBLE AND RETRACTABLE REAMER ELEMENTS 4 Claims, 5 Drawing Figs.

[52] U.S.Cl 175/267 [51] Int. Cl E21b 9/26 [50] Field of Search 175/267,

Primary Examiner-Nile C. Byers, Jr. Attorney-Charles E. Lightfoot ABSTRACT: A reamer for use in a drilling string for enlarging, scraping or smoothing a well bore, and having extensible and retractable cutting members operable by the pressure of the drilling fluid circulated through the string during the drilling operation. The cutting members may include a plurality of telescopingly arranged elements movably positioned on the body of the tool for radial movement inwardly and outwardly thereof relative to window openings in the body and having seal forming means positioned to prevent leakage through the openings. The cutting members and body are formed with inwardly and downwardly sloping end faces positioned for coaction to allow the cutting members to move inwardly toward their retracted position, aided by gravity, when the internal pressure in the string is shut off, and the members are also formed with beveled external, upper end faces, posi-v tioned for engagement with irregularities in the well bore to move the members toward their retracted positions upon upward movement of the string during the removal of the same from the bore.

PATENTEUJANISISTI 5 2 sum 1 0F 2 Lafayette E. Gilreath 8 Charles H. Pollard IN VLiN'l ()RS MZW ATTORNEY P/TENTEDJAHI 919m SHEET 2 BF 2 Lafayette E. Gilreath 8 Charles H. Pollard INVEN'IORS BY my 9r TTORNE Y REAMER WITH EXTENSIBLE AND RETRACTABLE REAMER ELEMENTS BACKGROUND OF THE INVENTION In the drilling of wells by the rotary drilling method, it is customary to make use of a tubular drilling string to whose lower end a drilling bit is attached whose diameter is substan tially larger than that of the string. During the drilling operation a suitable drilling fluid, such as drilling mud. is circulated downwardly through the string and upwardly in the annulus of the bore about the string to carry away cuttings and lubricate the drill.

The well bore produced by this method is almost never entirely vertical and frequently has curved or sloping portions, so that portions of the string are often in contact with the wall of the bore, which results in the formation of key slots at various locations in the bore, which slots are of substantially smaller diameter than the drilling bit and any drill collars employed therewith.

Upon attempting to withdraw the drilling string from a well having such key slots, there is a tendency for the string to be straightened by the upward pull exerted on the string, thus tending to pull the string laterally into the key slots and causing the drill collars and bit to become stuck in the bore.

Various devices have been employed to avoid the above difficulty, such as centralizers, key-seat reamers and broaching tools. connected into the string. Tools of this character, may, however. increase the difficulty by themselves becoming stuck in key slots. necessitating laborious and time consuming operations for the releasing and withdrawing of the string.

SUMMARY OF THE INVENTION Briefly stated, the present invention comprises an expansible and retractable reaming tool comprising a tubular body. adapted to be connected into a drilling string and formed with peripherally spaced window openings whose upper and lower ends are formed with radially inwardly and downwardly sloping faces. Extensible and retractable cutter members are movably mounted in the window openings for radial movement to extended positions to engage the outer extremities of the members with the surrounding wall of a well bore and retracted positions in which the members are substantially flush with the outer surface of the body. The cutter members are formed at their upper ends with beveled, external end faces positioned for engagement with irregularities in the bore, upon upward movement of the tool to urge the members toward their retracted positions.

The members are also formed with upper and lower inwardly and downwardly sloping faces positioned for coaction with the end faces of the window openings to allow the members to be urged by gravity toward their retracted positions. The cutter members may be made up of a number of telescopingly arranged sections between which seal forming means is positioned and similar seal forming means is provided between the members and the body in the window openings to prevent leakage into or out of the string.

The cutter members are adapted to be extended-by the pressure of fluid in the string and are formed with means positioned for coaction with the internal surface of the body externally of the window openings to limit outward radial movement of the members.

The invention has for an important object the provision of a reaming tool for use in a well drilling string embodying extensible and retractablev cutter members extensible by the pres sure of fluid in the string and having means to allow the retraction of the members under the influence of gravity when such pressure is removed.

Another object of the'invention is to provide a reamer of the kind referred to having extensible and retractable cutter members and embodying means for causing the members tobe.

moved toward their retracted positions in response to engagement of the members with irregularities in the well bore during removal ofthc string therefrom.

A still further object of the invention is to provide a well bore reamer of the type mentioned whose cutter members are constructed to enable the same to be easily disassembled for detachment from the body and reassembled therewith for pur poses of maintenance and repair.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS FIG. I is a vertical, central. cross-sectional view of a preferred embodiment of the well reamer of the invention, showing the same in its extended or expanded condition;

FIG. 2 is a cross-sectional view. taken along the line 2-2 of FIG. I, looking in the direction indicated by the arrows;

FIG. 3 is a side elevational view, partly broken away and partly in cross section, and on a reduced scale, showing a portion of a well bore with the reamer of the invention in an operating position therein. and illustrating the manner in which the same is operated;

FIG. 4 is a view similar to that of FIG. 1. illustrating a somewhat different form of the invention, showing the same in an extended condition; and

FIG. 5 is a fragmentary view. similar to that of FIG. 4. showing the reamer in a retracted condition.

DETAILED DESCRIPTION OF A PARTICULAR EMBODIMENT OF THE INVENTION Referring now to the drawings in greater detail the reamer of the invention comprises a tubular body 10, of the character of a section of drill pipc, adapted to be connected into a drilling string. as by means of an externally threaded pin portion 12 at one end of the body and an internally threaded box portion 14 at the other end thereof. The body is formed mediate its ends with a number of peripherally spaced externally thickened portions 16 whose ends are formed with external tapering faces 18 and 20.

Each of the thickened portions 16 has a longitudinally elongated. central. window opening therein. in communication with the bore 22 of the body and leading to the exterior thereof, and which may be formed with parallel longitudinal sidewalls 24 and with upper and lower, downwardly and inwardly sloping, rounded end walls 26 and 28, respectively.

An extendible and retractable cutting or reaming member is slidably disposed in each of the window openings, which element, as illustrated in FIG. I to 3, is formed with inner and outer parts 28 and 30, respectively, which may be detachably secured together, as by means of screws or bolts 32. The screws 32 are countersunk in the outer part 30 in counterbores 33, to permit the application to the outer surface of the outer part of a hard abrasive. or cutting material 34, such as tungsten carbide, or to allow the sharpening of the outer part to form cutting or reaming edges thereon. Such abrasive material may be conveniently attached to the outer part by brazing, or the like, and the heads of the screws 32 may be protected by plugs 36 of suitable material, such as asbestos, inserted in the counterbores.

The inner and outer parts are shaped to flt snugly. but slidably, in the window openings, the inner part having upper and lower curved end faces 38 and 40, respectively, which are shaped and slope to conform to the end faces 26 and 29, while the outer part has similarly shaped upper and lower end faces 42 and 44.

The outer part also has suitable means for limiting its inward movement in the window opening, such as the external projections or flanges 46 at its outer end positioned for engagement with the external surface of the body 10 beyond the sides of the window opening. while the inner part 28 is formed with projections for engagement with the internal surface of the body beyond the sides of the window opening to limit outward movement of thecutter members in the opening.

Suitable seal forming means, such as the O-ring 50, is post-- tioned for sealing engagement with each of the cutter elements and the body. in the window opening, to prevent leakage therebetween in all positions of the cutter members.

In making use of the well reamer, constructed as described above, the tool is connected into a string of pipe such as a drilling string, having a drilling bit attached to its lower end and lowered therewith into a well bore B, as seen in FIG. 3. During the drilling of the well, the pressure of the drilling fluid being circulated through the string and the annulus surrounding the same will exert a force on the cutting or reaming members of the tool tending to extend the cutters into engagement with the surrounding wall of the bore, and this force may be regulated by increasing or decreasing the pressure of the drilling fluid.

When the drilling string is to be withdrawn from the well, the pressure of the drilling fluid will be cut off so that the cutters may retract under the influence of gravity, and in the event that the cutters should engage any projections or irregularities in the bore, as the string moves upwardly therein, the cutters may slide freely along the downwardly and inwardly sloping end faces 26 and 29 of the window openings, thus al-- lowing the cutters to retract to positions substantially flush with the outer surface of the body, whereby sticking of the tool in the well bore or damage to the cutters is effectively prevented.

A somewhat different form of the invention is illustrated in FIGS. 4 and 5. wherein the extensible and retractable reamer or cutter members are formed in a number of telescopingly arranged parts to enable the tool to be used in well bores of substantially different diameters. i

In this form of the invention, eachcutter member has inner and outer parts 28' and 30' similar or identical to the parts 28 and 30 previously described, and additional telescopingly arranged parts 60 and 62 by which the parts 28' and 30' are movably mounted in the window opening of the body.

In this case the innermost one 60 of the telescoping parts 60 and 62 is formed with curved, sloping, external end faces 64 conforming to the shape of the curved end faces 26 and 29 of the window opening and is snugly but slidably fitted in the opening. The part 60 also has lateral projections 66 at its inner end positioned for engagement with the inner surface of the body adjacent the window opening to limit the outward movement of the part therein.

The parts and 62 are formed with interengageable portions 68 and 70, respectively, positioned for engagement to limit relative movement of the parts and the part 62 has a portion 72 positioned for engagement with the inner end projection 48' of the part 28 to limit outward movement of the part 28' relativeto part 60 and to cause the part 60 to be extended with the part 28' upon extension of the cutter.

Suitable seal forming means such as the O-rings 50', 74 and 76 are positioned to form fluid tight seals between the parts 28' and 62. between parts 60 and 62 and between part 60 and the body in the window opening. in all positions of the parts.

In other respects the form of the invention illustrated in FIGS. 4 and 5. is similar to that of H08. 1 to 3, and is similarly operated.

ln assembling the cutter members with the body, the inner part 28, in the form of the invention shown in FIGS. l. 2 and 3. may be inserted into the window opening through the bore of the body and the outer part 30 then attached to the inner part. while in the form of the invention illustrated in FIGS. 4 and 5 the inner parts 60 and 62 and inner part 28' may be similarly positioned one within another in the window opening and the outer part 30' then attached to the part 28. It will also be apparent that the cutter members may be disassembled and removed from the body in an obvious manner by reversing the above described method of assembly.

It will thus be apparent that the invention constructed as described above, provides a reamer device for employment in well drilling strings which is of simple design and rugged construction, in which the cutter members may move readily toward retracted positions in response to engagement of the members with irregularities in a well bore and wherein the parts are easily replaceable for purposes of repair.

The invention lS disclosed herein in connection with particular constructions and arrangement of the parts thereof, which are intended by way of illustration only. it being evident that various changes can be made therein within the spirit of the invention and the scope of the appended claims.

lclaim:

l. A well reamer comprising a tubular body adapted to be connected into a well string for rotation and lowering with the string in a well bore, and having peripherally spaced window openings, cutter members movably mounted in the window openings for radial movement to extended positions projecting outwardly from the body under the influence of the pressure of fluid in the body and to retracted positions substantially flush with the external surface of the body, said body being formed with upper and lower downwardly and inwardly sloping end faces in said window openings, and said members being formed with end surfaces shaped for coaction with said end faces to cause the members to move radially inwardly and downwardly away from said wall upon movement of said members away from said extended positions.

2. The well reamer as claimed in claim 1 wherein each of said members includes an inner part and an outer part detachably secured together and means on said inner part positioned for coaction with said body to limit outward movement of the member in the opening.

3. The well reamer as claimed in claim I wherein each of said members includes telescopingly arranged parts slidable relative to each other radially of the body and means on said parts positioned for coaction to limit movement of the parts toward said extended position.

4. The well reamer as claimed in claim 3 including seal forming means for each of said partspositioned for coaction with the parts and body to prevent the outflow of fluid from the body through said window openings in all positions of the members. 

1. A well reamer comprising a tubular body adapted to be connected into a well string for rotation and lowering with the string in a well bore, and having peripherally spaced window openings, cutter members movably mounted in the window openings for radial movement to extended positions projecting outwardly from the body under the influence of the pressure of fluid in the body and to retracted positions substantially flush with the external surface of the body, said body being formed with upper and lower downwardly and inwardly sloping end faces in said window openings, and said members being formed with end surfaces shaped for coaction with said end faces to cause the members to move radially inwardly and downwardly away from said wall upon movement of said members away from said extended positions.
 2. The well reamer as claimed in claim 1 wherein each of said members includes an inner part and an outer part detachably secured together and means on said inner part positioned for coaction with said body to limit outward movement of the member in the opening.
 3. The well reamer as claimed in claim 1 wherein each of said members includes telescopingly arranged parts slidable relative to each other radially of the body and means on said parts positioned for coaction to limit movement of the parts toward said extended position.
 4. The well reamer as claimed in claim 3 including seal forming means for each of said parts positioned for coaction with the parts and body to prevent the outflow of fluid from the body through said window openings in all positions of the members. 